Measurement of the angular distribution in p̄p → ψ ( 2 S ) → e + e −
نویسندگان
چکیده
We present the first measurement of the angular distribution for the exclusive process p̄p→ ψ(2S) → e+e− based on a sample of 6844 events collected by the Fermilab E835 experiment. We find that the angular distribution is well described by the expected functional form dN d cos θ ∝ 1 + λ cos2 θ∗, where θ∗ is the angle between the Preprint submitted to Elsevier Science 28 February 2008 antiproton and the electron in the center of mass frame, with λ = 0.67 ± 0.15 (stat.) ± 0.04 (sys.) The measured value for λ implies a small but non zero ψ(2S) helicity 0 formation amplitude in p̄p, comparable to what is observed in J/ψ decays to baryon pairs.
منابع مشابه
Ja n 20 05 Measurement of the angular distribution in p̄p → ψ ( 2 S ) → e + e −
We present the first measurement of the angular distribution for the exclusive process p̄p→ ψ(2S) → e+e− based on a sample of 6844 events collected by the Fermilab E835 experiment. We find that the angular distribution is well described by the expected functional form dN d cos θ ∝ 1 + λ cos2 θ∗, where θ∗ is the angle between the Preprint submitted to Elsevier Science 7 February 2008 antiproton a...
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